John dunn stark



(No Model.)

J. D. STARK.

SLIDE VALVE FOR ENGINES.

No. 484,903. Patented Oct. 25, 1892. @ji/cy ...man il Q 1 PATENT Fries.

JOHN DUNN STARK, OF NEW YORK, N. Y.

SLIDE-VALVE FOR ENGINES.

SPECIFICATION forming part of Letters Iatent No. 484,903, dated October 25, 1892.

Application led August v3, 1891.

To all whom it may concern.-

Be it known that I, JOHN DUNN STARK, a citizen of the United States, and a resident of New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Slide-Valves for Steam-Engines, of which the following is a specification.

My invention relates to improvements in balanced slide-valves and their seats; and the objects of my invention are, first, to get rid of the excessive friction which is caused by steam-pressure on the valve, and, second, to make a steam-engine more easily governed and controlled. I attain these objects by the mechanism illustrated in the accompanying drawings, in which- Figure l is a perspective view of the valveseat; Fig. 2, a like view of the valve; Fig. 3, a sectional view of the valve, and Fig. 1l a like view of the same in position on its seat.

Similar letters refer to similar parts throughout the' several views.

If over the surface A B, Fig. l, we put a plate or cover, we will have a new form of steam-chest, which may be cast as a part of the cylinder instead of being separate. In the drawings the cover is left olif to expose the ports may. The opposite ports in the side B are seen only in Fig. 4.

The valve, Fig. 2, is moved over and between the opposite ports and seats by means of the connecting-rod J, Fig. 4, which is connected with the eccentric and with the valve, as shown in the drawings. In its motion the valve runs on a small guide at each corner, by which it is retained in the proper position to allow steam to pass and press on all sides of its free surface.

The valve, Fig. 2, is made in two parts G and H, with their backs adjoining in the seam E. Over this seam is placed the ribbon D D, of metal or other suitable material, which, being flexible, renders the seam steamtight by virtue of the pressure of steam all round the valve. If the back of each part of this valve be of the same size as its face, it must be held against its seat by means of springs between its two parts; but if the face of each part is made a little larger than its back, as shown in Fig. 2, the valve will adjust itself by slight steam-pressure without Serial No. 401,615. (No model.)

the springs. Recours@ may be had to both springs and steam-pressure, if desired.

The two parts H G of the valve are connected together, so as to move parallel to each other, by means of the cross-pieces a b, which are pivoted at one end to the two parts of the valve, Fig. 3, and at the other end to the slides c e, which move freely parallel with the two parts of the valve as they act automatically in taking up any wear caused by the friction between the valve and its seat. By this means of connecting the two parts of the valve one end cannot be raised from its seat without raising the Whole length of the valve. If the part A, Fig. l, be placed directly over the ordinary steam-ports and the ports 0c z y be made to pass through it from side to side and to open into the old ports, we may dispense with the part B and connect two ordinarilyshaped valves together, so as to run on the two opposite seats thus formed. Then if we construct one or both valves in two parts and connect said parts in a manner described in reference to the two parts of the valve, Figs. 2 and 3, these twin valves will also adj ust and balance themselves. It will be seen that while the ports y y', Fig. 4, are open steam rushes into the cylinder through these and the apertures d d', and at the same time the exhauststeam goes through b b a; fr and the opening O, passing through the valve and through the exhaust-port a a, as shown by the arrows.

What I claim as my invention, and desire to secure by Letters Patent, is-

l. A balanced slide-valve made in two similar parts or halves, which are connected together by means of cross bars or links pivoted to each, so as to secure accurate parallel motion, substantially as set forth.

2. A steam slide-valve composed of two similar parts, which are connected together by cross-pieces that produce parallel action of said parts over the seam, between which is a iiexible ribbon, substantially as set forth.

3. The double slidevalve, in combination with the double set of steam-ports and valveseats, the ribbon over the joint between the two parts, and the parallel connection of the same, as and for the purpose set forth.

4. The double steam slide-valve, in combination with the double valve-seat, the crossbars which produce parallel action of the two IOO the parallel connection of the two parts of the valve by means of cross-bars, the ribbon over r 5 the seam between the said parts, the double valve-seats, and the double set of ports, all substantially as set forth.

Signed at New York, in the county of New York and State of New York, this 1st day of zo August, A. D. 1891.

JOHN DUNN STARK.

Witnesses:

ELLA F. BRAMAN, Jos. C. BRAMAN. 

